Swimming pools range in size from small inflatable pools to large Olympic size pools, and the even larger pools now used at water parks. Pools can be classified as either above-ground or in-ground; however, there are variations of these classifications which are designed and constructed to fit the circumstances. Above-ground pools are generally constructed of vinyl and metal or wood; they are easy to build and less costly to construct than in-ground pools, but are less durable. In-ground pools can be constructed of a number of different products, including fiberglass, steel and concrete. Pools constructed inside buildings require appropriately designed equipment to ensure appropriate humidity levels and the required ventilation.
The design of a swimming pool is based on several factors, including: the use of the pool, desired shape, size, and depth; budget; and site constraints. Pools normally range in depth from 3’-0” to 12-0”, but specially-designed diving pools can be as deep as 20 feet. There are many elements to consider in pool placement; these include sun or shaded areas; low spots at the site; the water table in the area; and utilities located below ground.
One of the initial steps in constructing an above ground pool (whether from a kit or from individual components) is to level the ground. The most efficient method of doing this is to use a laser level. The framework is assembled and, to reduce the risk of puncture, sand is used to smooth out the ground where the bottom of the pool will be located. The plumbing piping is laid out at this time also. Finally, a vinyl liner is secured over the pool frame. The pool can be filled with water as soon as the vinyl is secured and the bottom smoothed out. Then, smooth it out again and fasten the liner permanently. This type of pool, although usually the least costly to install, is more susceptible to damage and is typically less durable than in-ground pools. Once the pump and filtering system are hooked up, the pool is ready to be placed into operation. Another advantage to this type of pool is the relative ease with which it can be moved.
Another type of pool often seen is an in-ground pool, and they are almost always professionally installed. Fiberglass is one material used for in-ground pools, and the use of fiberglass allows an almost endless number of shapes. A form is required, but once the form is constructed, the fiberglass pool can be molded into the form, making the same shape for the basin. Installation of the pool requires a construction crew digging a hole that is accurately sized for the pool. Next the necessary plumbing is installed and sand is added to the underside of the basin, so that the fiberglass mold is evenly supported and is level. The fiberglass basin is then lowered into the hole. It is essential that the pool is level so that any concrete or permanent walks or decks that are installed are level with the top of the pool.
Following leveling, the filter, heater (if applicable), pump, and piping are all connected. Then, the area around the pool can be back-filled and the deck (usually concrete) can be poured. Finally, things like ladders and diving boards can be installed. The next step is to fill the pool, inspect the plumbing and begin use.
There are several other types of in-ground pools. One that is popular is a gunite (a special concrete material that can be blown using hoses and nozzles) pool. For this type of pool, a construction crew digs a hole that closely resembles what the final shape of the pool will be. A framework grid of re-inforcement steel is then assembled to the shape of the hole. The reinforcement bars are secured together and then a heavy coating of gunite is sprayed onto the grid. The construction crew trowels the gunite until it is smooth. Then, it is left to set up. Once set up, a finish can be applied. Pressure applied concrete such as gunite is more often used in warmer climates, where the freeze/thaw cycle is not present or is rare.
Another in-ground pool type is a poured-concrete pool. This type of pool construction requires highly skilled trades and supervision. After a hole is dug that is larger than the finished pool will be, concrete forms, with appropriate reinforcing and form ties, are assembled. After the forms are installed, a concrete pump is usually used to then pump the forms with the required amount of concrete. After the forms are removed, the plumbing is installed behind the wall and under the floor, and then concrete is installed for the floor. Still another type of pool that is usually an in-ground pool is one that has the walls and floor made of stainless steel. There are several "hybrid" in-ground pools that are not too often seen. These will use fiberglass or stainless steel as the walls, and then the floor will be poured with concrete.
The water clarity and purity of swimming pools are achieved by filtration and chemical treatment. Surfaces of most pools are skimmed automatically by the installed equipment. Skimming removes the top surface of water and filters it, removing bugs, debris, and body oils. The bottom of a pool requires vacuuming to remove debris and sediment.
The chemical balance in a pool must be carefully monitored and corrected as required. Without the proper chemical balance in a pool, it could be unsafe to use. Water with too much of one chemical and not enough of another can irritate the skin and eyes and can cause the water to become cloudy. It can also damage some parts of the filtering system as well as other parts of the pool. Chlorine is one of the most effective and popular chemicals to add to the pool water to kill disease carrying microorganisms. Chlorine may be found in powder form, liquid form, or powder formed into tablets. According to the pool experts, chlorine can be added anywhere in the filtering cycle, but it is generally recommended that chlorine be added after the filtering process, using a chemical feeder. It is also generally recommended that chlorine not be added directly to the pool or added by using tablets in skimmer boxes, because the chlorine tends to be too concentrated.
Another concern is that the correct pH balance is maintained in a pool. pH is a measure of a fluid’s total acid-alkalinity balance, with a reading of 7.0 considered balanced. Water that is too acidic will corrode metal parts of the system, cause some etching on the surfaces of some materials, and cause skin irritation, while water that is too alkaline scales the pool surface and plumbing equipment and can make the water cloudy. Two other problems with chemically unbalanced water are that the chlorine will not destroy microorganisms as effectively if the water is too alkaline, and it will dissipate much more quickly if the water is too acidic. Since the water pH needs to be in balance, maintaining the proper amount of chemicals in a pool is a continual process.
There must also be a way to make up for the water that is lost throughout the day. Water will be lost due to evaporation, backwashing, and splashing over the sides of the pool during use. On a hot summer day, it is not unreasonable for a 170,000 gallon pool to lose 350 gallons.
Various pool accessories are available for use in and around the area. Lights, heaters, fountains, ladders, and covers are common accessories. A deck, either concrete or wood, is also a common feature used around a pool.
See also: Swimming Pool Plumbing Systems